Bootleg breeders are illegally smuggling thousands of puppies into Britain to meet Christmas demand, a dog welfare charity has warned.

Nearly 100 were seized at the border in one week, the Dogs Trust said, labelling the record clampdown "just the tip of the iceberg".

High demand for trendy breeds like pugs, dachshunds and French bulldogs helps fuel the "sickening trade", which can net unscrupulous farmers tens of thousands of pounds.

Pups suffering from behavioural and health problems are among thousands trafficked in "shocking conditions", many from central and eastern Europe, the charity said.

Some as young as four weeks old resort to vomiting and eating their own faeces as they are smuggled across Europe in cramped spaces with no air conditioning, its investigation found.

In 2016, some 275,876 dogs travelled to Great Britain, more than treble the recorded number in 2011.

Dogs Trust veterinary director Paula Boyden said: "Buying an illegally imported puppy could potentially cost well-meaning but unsuspecting families thousands of pounds in quarantine and vet bills and emotional heartache for the family if the puppy falls ill or worse, dies."

In one recent case, seven cane corso pups were found with infected wounds after having their ears and tails illegally cropped and docked with scissors and vodka.

Just under half (48%) of prospective buyers said they would be concerned if a puppy they purchased was imported illegally, a recent Onepoll survey found.

The findings suggest the public do not know enough about the horrors of the trade, the trust said.

It has compiled advice to help people avoid purchasing illegal pups.

They should ask to see the mother and pup together, and visit the new pup more than once and get paperwork before taking it home.

Buyers should report suspicious sellers and take new puppies to their own vet for a health check as soon as possible.

The charity said buyers should not meet anywhere that is not the pup's home, or buy from anyone who can supply various breeds on demand.

People are advised not to buy a puppy that looks too small or underweight, or feel pressured into buying.

The charity added it was also worried about a "shocking new trend" of heavily pregnant bitches being smuggled into the UK to give birth.

Its Puppy Pilot scheme has found more than 600 smuggled dogs a home after being established two years ago to prevent poorly pups being put down.

Ms Boyden added: "We continue to be astounded at the lengths these deceptive breeders and dealers will go to in order to illegally import puppies to make huge profits with complete disregard for their wellbeing.

"The cases we are seeing on a weekly basis are horrific and need to stop."

The maximum sentence for illegal importers is just three months under the Non-Commercial Movement of Pet Animals (Amendment) Order 2011.

The trust labelled it a weak deterrent, adding: "We urge the Government to improve this failing legislation. This includes increasing penalties for those illegally importing puppies and a significant overhaul of the pet-checking system at ports."

A spokesman for the Department for Environment, Food and Rural Affairs said: "We are cracking down on animal trafficking with one of the toughest pet border checking regimes in the world.

"Every pet dog travelling to the UK has both microchips and passports checked to make sure they are properly vaccinated and old enough to travel.

"As we leave the EU, we are looking at how we can further strengthen checks to stop this abhorrent illegal trade."